I have a leader stacked with an infantry unit in a multihex line formation. I think the leader is in both hexes. So is his command span traced from both hexes, making for more of an ellipse shaped command radius?

8.1.1.1 With Multi-Hex Units: When a leader is stacked with a multihexunit it may be in only one of the unit’s constituent hexes.NOTE: Use Extended Line Markers instead of straddling a hexsideto avoid a wobbly stack of units.

As I recall, other than what's stated in the Regulations, La Bataille has never cut leaders any slack on stacking with a multi-hex units and gaining that hex or two of command range (Battles from the Age of Reason does this, however). Note, though, for this game that Ed allowed use of "Communicating Battalions" to extend command range, something that did not carry over to the Regulations.